Patent Document 1 discloses a battery state monitoring system that can be effectively and easily used between battery packs in which the number of battery cells is different in each case. The battery state monitoring system includes a battery state notification unit. The battery state notification unit is provided with a plurality of sub-units each of which corresponds to a predetermined number of battery cells. In addition, each of the sub-units generates battery state information including information, which represents a battery cell state corresponding to the sub-unit on the basis of a cell voltage signal in correspondence with an inter-electrode voltage, and a cell temperature signal in correspondence with a voltage that is output from a temperature sensor unit, and the sub-unit transmits the battery state information to an external apparatus.
Patent Document 2 discloses a battery cell monitoring integrated-circuit capable of obtaining high reliability. The battery cell monitoring integrated-circuit is provided in correspondence with a plurality of battery cells which are electrically connected in series. In addition, the battery cell monitoring integrated-circuit includes a signal input terminal through which a one-bit signal in a high level or a low level is input, a signal output terminal through which a one-bit signal in a high level or a low level is output, and a unit that detects whether or not over-charging or over-discharging is present in the plurality of battery cells. In addition, in a case where abnormality of over-charging or over-discharging is present in the plurality of battery cells, a one-bit signal representing the abnormality is output from the signal output terminal.
Patent Document 3 discloses a voltage equalizer that equalizes a voltage between both ends of each electrical storage device of an assembled electrical storage apparatus in which a plurality of single electrical storage devices are connected in series. The voltage equalizer includes a plurality of voltage regulation units which include a pair of terminals, and which charge or discharge a plurality of electrical storage devices connected in series between the terminals, and a control unit that controls the plurality of voltage regulation units. At least one terminal of each voltage regulation unit is connected to a connection point of the electrical storage devices which are connected in series, and one terminal of one or a plurality of other voltage regulation units is connected between the pair of terminals with one or a plurality of the electrical storage devices interposed therebetween.
Patent Document 4 discloses a battery charging apparatus that is capable of accurately detecting a completely charged state of a battery, and is capable of detecting a kind of a battery pack. The battery charging apparatus includes a charging control unit, a charging rate control unit, and a charging mode selection unit. The charging control unit outputs a charging enable signal, which is based on a battery temperature signal, a battery kind signal, a battery voltage signal, and an output from a voltage division unit, to a charging current control unit, and outputs a charging control signal configured to control a charging rate of a battery pack, a mode control signal configured to allow the charging current control unit to operate in any one of a constant-current charging mode and a constant-voltage charging mode in accordance with the kind of the battery pack, and a charging current compensation signal that makes the amount of a charging current and the amount of a reference current equal to each other. The charging rate control unit regulates a signal of a control terminal in accordance with the charging control signal so as to control the charging rate. The charging mode selection unit selectively outputs a constant-voltage control signal to the control terminal by using the mode control signal.